In some surgical procedures, a particularly good example of which involves operations on the spinal cord, bone is broken away to provide access to the area requiring surgery. Where the bone has been broken, the remaining bone has open, porous areas and these areas typically ooze blood. Bone hemostasis is required to allow clear visualization of the surgical site by the surgeon during the operation, and also to prevent post-operative complications from blood accumulation.
During any surgery, it is necessary to stop blood ooze, or adsorb the blood, as best as is possible. With the major advances in microsurgery, even small amounts of blood provide intolerable obstructions in the surgeon's confined microscopic field of view. Because the microscopic field of vision during these operation has become increasingly confined, distractions of the surgeon from the immediate surgical field cannot be tolerated.
The tissue structures involved in microsurgery are extremely delicate, and even small amounts of blood obscure the anatomy. For surgery to proceed without unacceptable injury requires perfect clarity of vision. In a spinal operation, for example, the oozing bone is proximate to the very delicate neural structures. Stopping the ooze from the irregular surfaces is difficult and the surface must be filled with a compressing material to stop the bleeding. The technique to compress material into the bone surface requires a great deal more force than can be tolerated by the adjoining vulnerable neural structures, which are at risk with even the most careful techniques. Thus, a slip during bone hemostasis could be fatal. Preserving the vital structures while obtaining the required visualization warrants the utilization of the most advanced and delicate techniques. Simplifying the procedures and reducing the number of steps as much as possible is very important.
In microsurgical techniques, the surgeon is isolated from an ability to interact with the instrument field. There is very limited access to the microscopic field, also limiting the help available from assistants. The surgeon has come to depend on his own hands to provide the speed and efficiency needed to accomplish the highly delicate tasks of the microsurgical operation. Procedures which decrease the number of steps are critical to furthering the ability to accomplish microsurgery advances. Those which decrease the number of instruments to accomplish a maneuver are equally critical.
The health of the patient is also a factor. With advances in the understanding of infection and wound healing, incisional blood accumulation has become a known risk factor, and must be minimized. Medullary bone ooze is a major source of incisional bleeding in many surgical procedures.
Bone wax has been utilized since the late 1800's as an effective bone hemostatic agent. Typically, a metal instrument such as a spatula is used to bring a mass of bone wax from the surgical tray into the situs of the surgery, where it is pressed into the open bone; in effect sealing off the bleeding surface. Given the often irregular oozing surface, the metal instrument often proves to be too rigid, and a more conforming gloved finger may be used. Even a finger, however, often provides inadequate to conform the bone wax to bone spicules. Additionally, glove puncture may occur, exposing the surgeon and the patient to cross infection, not only from bacteria and hepatitis, but AIDS and other infections as well. Furthermore, the nurse or other operating room assistant must first manipulate the bone wax into a size that can be inserted into the situs of the operation. The resulting wax pieces are of inconsistent size, softness and texture.
Other bone-conforming interfaces, such as cotton materials, have been used, to attempt to force the bone wax evenly into the irregular bone surface. However, bone wax will not stick to wet cotton fibers. Furthermore, use of additional materials requires additional steps during the surgical procedure and also introduces an additional source of imprecision in the handling of the bone wax.
Although a nurse provides as much assistance as possible to the surgeon during the surgery, to achieve bone hemostasis the surgeon still must generally move one hand from the incision to a tray where the bone wax, and separately cotton sponges, have been placed by the nurse. Ordinarily the tray may already be wet with disinfectant or other liquids. Bone wax is difficult to adhere to an already wet surface. Ordinarily, the doctor should not take his eyes off the incision, but in some cases that might be necessary. It is critical, however, that the surgeon keep his eyes steadily on the incision as much as possible, and have both hands free to perform the operation, rather than be forced to manipulate bone wax onto and off of the tray. As the surgical procedures become ever more precise and taxing to the surgeon, and limit the ability to use an assistant in the small, critically delicate areas of operation, efficiency and simplicity of movement become of paramount importance. Reduction in the number of steps of surgery is thus requisite to advances in microsurgery.